The concept of electric power system state estimation was initially applied to transmission networks to estimate node voltages, generator power outputs, load demands, and branch power and current flows at a given point in time based on real-time telemetered measurements. This application has generally assumed imperfect but highly redundant measurements, as well as exact power system model topology and electrical parameters. Network topology estimation is an integral part of state estimation and a critical component of modern Energy Management Systems (EMS) or Distribution Management Systems (DMS). The conventional network topology processing (NTP) function monitors the statuses of switching and switchable devices, and determines the model input to the state estimator. As used herein, the term “switching device” encompasses circuit breakers, isolator switches, fuses and other circuit elements that perform the functions of one or more of those devices. Circuit breaker statuses, isolator switch statuses, fuse statuses, and transformer tap positions are examples of real-time inputs used by the network topology processor. A conventional NTP determines the connectivity of the electrical network, taking as input a complete model of the network, comprising nodes and switching devices. The NTP reduces the node-switching-device model to a “bus-branch” model, where the concept of bus defines a maximal subnetwork interconnecting nodes and closed switching devices only. As used herein, the term “bus” includes groups of neighboring buses considered as a single bus, and also includes distribution network nodes. The objective of the conventional NTP is to eliminate all switching devices from the network model, by instantiating their “open” or “closed” statuses. The NTP achieves this instantiation by processing the switching device user-defined, measured, scheduled or normal status, as available in that order of precedence. The conventional state estimation sub-program then solves and analyzes the resulting bus-branch model. Undetected switching device status errors during estimation show up as analog measurement errors in the solution, which are difficult to distinguish from actual analog measurement errors. Hence, reliable and prompt detection of the switching device statuses is crucial for accurate state estimation. The output of the state estimator is a critical input to nearly all other network analysis, security, control and stability assessment applications.
In distribution grid management, a critical task of a system operator is to take quick action to restore continuity of electric power supply following forced outages. For many distribution networks, however, the measurement redundancy is so low that the first and often only indications of an outage are telephone calls from customers reporting loss of supply. In the mostly radial topologies of a distribution network, the opening of a normally-closed switching device generally results in some loss of electric power supply. Clearly, the analysis performed by aggregating and mapping multiple customer calls into a suspected common network device, such as a fuse, which is then suspected to be open, is an instance of network topology estimation. Many existing outage management systems (OMS) are still based on the process of call aggregation, which can take from tens of minutes to hours (if happens at night, for example) to identify the culprit device. An automatic procedure that will reduce the detection time will lead to a much better quality of service and higher revenues to utility companies.